JP6063152B2 - Shadow detection device for solar power plant using optical fiber - Google Patents

Description

  The present invention mainly relates to solar power generation, and more particularly to an apparatus for detecting unevenness (for example, shadow) of solar radiance that can occur in an element array of a solar power generation system.

  Large-scale power generation using solar energy has evolved as an attractive source for clean and highly efficient power generation that can be freely used and essentially inexhaustible, that is, capable of generating power from the sun. continuing.

  As a solar power generation system that directly converts solar radiation into electricity, there is a solar (eg, photovoltaic (PV)) array that is an aggregate of a plurality of solar modules combined. The solar module is composed of a plurality of interconnected solar cells (so-called strings). These cells directly convert solar energy into direct current (DC) electricity due to the photovoltaic effect.

  The output power of the solar module is approximately proportional to the illuminance of solar radiation received by the module. It should be understood that in certain applications (e.g., solar power plants, building-integrated PV systems, etc.), solar radiation (so-called radiation) to the photovoltaic modules may be non-uniform. A possible cause of non-uniform solar radiation is a decrease in solar radiance (eg, shadows) due to clouds, nearby trees and / or man-made structures, dirt, and the like. Whatever the cause, the shadowing of the solar module leads to a decrease in the module performance. For example, the characteristics of the solar module's current-voltage (IV) and power-voltage (P-V) curves are substantially affected by the illuminance of solar radiation received by the module. Furthermore, if the solar cell is shaded, it may have an adverse effect. This is because the shaded cell behaves like a load (i.e. draws current), which can create undesirable hot spots. It should be understood that the lack of optimal performance as a result of shadows is not limited to systems using direct conversion elements. For example, indirect conversion systems that use elements such as solar collectors are also affected by the presence of shadows.

  It is known to use a global solarimeter to measure solar radiance. An all-pyrometer is a device that responds to heat and is therefore relatively slow in response. For example, a global solarimeter is not suitable for accurately detecting rapid variations in solar radiance, such as may occur due to cloud movement. It is also known to use a PV sensor to measure solar radiance. The PV sensor is composed of a solar cell, and its output power depends on the operating temperature of the solar cell. This means that temperature detection needs to be performed in order to offset the influence of temperature. Furthermore, the PV sensor is faster in response than the global solarimeter, but the measurement accuracy tends to be inferior to that of the global solarimeter.

  US Pat. No. 6,858,791

  In view of the above-mentioned problems, it is desirable to provide a highly reliable, highly accurate, relatively fast response, low cost device that reveals the presence of shadows in solar power generation systems. Will.

  Aspects of the invention can be realized by a solar power generation system that includes an array of multiple elements responsive to solar radiance. These elements are placed at respective locations in the field. The system further includes a plurality of optical fibers, each first end of the plurality of optical fibers being coupled to the element array and configured to receive solar radiance. The plurality of optical fibers further have respective second ends configured to output respective optical signals representing respective solar radiances for respective locations of the field. Optoelectronic circuits are coupled to receive respective optical signals from the plurality of optical fibers and to generate respective signals indicative of the presence of a shadow state at at least one or more of the respective locations of the field. A controller responsive to each signal from the optoelectronic circuit is configured to implement a control strategy for the element array, taking into account the presence of a shadow state at one or more of each location in the field.

  Another aspect of the present invention can be realized by an apparatus for revealing the presence of shadows in a solar power generation system having an array of elements responsive to solar radiance. These elements are placed at respective locations in the field. The apparatus includes a plurality of optical fibers and a first end of each of the plurality of optical fibers is coupled to the element array and configured to receive solar radiance. The plurality of optical fibers have respective second ends configured to output respective optical signals representing respective solar radiances for respective locations in the field. Optoelectronic circuits are coupled to receive respective optical signals from the plurality of optical fibers and to generate respective signals indicative of the presence of a shadow state at at least one or more of the respective locations of the field.

  Yet another aspect of the present invention can be realized by a solar power generation system that includes an array of photovoltaic modules arranged at respective locations in the field. The system further includes a plurality of optical fibers, and a first end of each of the plurality of optical fibers is coupled to the photovoltaic module array and configured to receive solar radiance. The plurality of optical fibers have respective second ends that output respective optical signals representing respective solar radiances for respective locations in the field. A photodetection device responds to each optical signal from the plurality of optical fibers. A processing device is coupled with the light detection device to process each light detection device output signal and generate respective signals indicative of the presence of a shadow state in at least one or more of the respective locations of the field. . A controller responsive to each signal from the processing unit is configured to implement a control strategy for the photovoltaic module array, taking into account the presence of a shadow state at one or more of each location in the field. Is done.

  The foregoing and other features, aspects, and advantages of the present invention will become better understood when the following detailed description is read with reference to the accompanying drawings, in which: In the accompanying drawings, like reference characters designate like elements throughout the drawings.

1 is a schematic diagram of an example solar power generation system (eg, a commercial scale PV plant) that includes an example of an apparatus that detects solar radiance unevenness (eg, shadows) according to aspects of the present invention. FIG. 3 is a schematic diagram of another embodiment of an apparatus for detecting unevenness of solar radiance according to an aspect of the present invention. 1 is a block diagram of one embodiment of a photoelectric circuit that is part of an apparatus for detecting unevenness in solar radiance according to an aspect of the present invention. FIG.

  FIG. 1 is a schematic diagram of an embodiment of a solar power generation system 10 capable of generating power using solar energy. The system 10 includes an array of elements responsive to solar radiance, eg, an array (or string) 12 of photovoltaic (PV) modules, each of which is an interconnected plurality of solar cells. 14. These elements are located at respective locations (eg, spaced apart) in the field 11 such as a practical scale solar farm, where the field 11 has a relatively large surface area (eg, potentially several). Need a hundred acres).

  As will be readily appreciated by those skilled in the art, the PV module 12 can be connected in the form of a series circuit (string) to obtain the desired voltage, and then to obtain the desired current. In addition, each string of such series-connected PV modules can be connected to each other in the form of a parallel circuit. One or more electronic converters (eg, inverters not shown) can be used to convert the DC power generated by all of their connected PV modules into grid compatible alternating current (AC). is there.

  Embodiments of the present invention are potentially cost-effective and high in detecting solar radiance irregularities (eg, shadows) that can affect one or more elements of system 10 (eg, PV module 12). A reliability device 15 is included. It should be understood that aspects of the present invention are not limited to systems that use elements capable of directly converting solar radiation into electricity. For example, the aspect of the present invention can be easily applied to a solar power generation system that uses an element that indirectly converts solar radiation into electricity, and an air conditioning system such as a solar collector.

  Examples of systems that can benefit from aspects of the present invention include photovoltaic systems, centralized photovoltaic systems, solar collectors, and the like. Accordingly, the foregoing description of a solar power generation system using PV modules should be construed as exemplary rather than limiting.

  In one embodiment, the PV module 12 includes a plurality of optical fibers 16 arranged to obtain solar radiance measurements that are representative of the shadowed state. In one embodiment, each first end 18 of each fiber is exposed to receive solar radiance, and each second end 20 of each fiber is at a respective location in field 11. Each optical signal representing each solar radiance is output.

  In one embodiment, at least one of the locations of the field 11 is coupled by coupling the optical fiber 16 with the optoelectronic circuit 22 to appropriately acquire, condition, and process the respective optical signal from the optical fiber 16. It is determined whether a shadow state exists in one or more.

  It should be understood that the number of optical fibers 16 that can be coupled to the element array can be selected to provide any desired spatial resolution for solar radiance measurements across the field 11. Thus, it should be understood that aspects of the present invention are not limited in any way by the number of optical fibers per PV module. Further, in FIG. 1, the respective first ends 18 of the optical fibers 16 are located at opposite longitudinal ends of the PV module or rack system. It should be understood that the specific position of each of the first ends 18 is not limited in any way. In one embodiment, the respective first end 18 of each optical fiber 16 can be located near the periphery of the field 11. Accordingly, the number and / or location of the optical fibers shown in FIGS. 1 and 2 should be construed as exemplary rather than limiting.

  In the embodiment shown in FIG. 2, the efficiency of transferring solar radiance to an optical fiber by optically coupling a plurality of magnifying lenses 24 to each first end 18 of the plurality of optical fibers 16. It is possible to improve. This can be a selection example suitable for climatic regions where solar irradiance is generally low (eg, regions of relevant latitude).

  FIG. 3 is a block diagram of one embodiment of a photoelectric circuit 22 that includes a data acquisition (DAQ) unit 30 that, for example, acquires optical signals from a plurality of optical fibers 16. It is a multi-channel DAQ unit that adjusts. In one embodiment, the DAQ unit 30 includes a main optical coupling box 32 that is coupled to the second end of each of the plurality of optical fibers. A photo detector 34, which may include one or more photo detectors, is arranged to receive the respective optical signals from a plurality of optical fibers coupled to the coupling box 32. As will be appreciated by those skilled in the art, standard multiplexing techniques can readily be used to reduce the number of photodetectors used in the photodetector 34. For example, a single photodetector can respond to optical signals from multiple optical fibers sampled sequentially at each time interval.

  The analog-digital converter 36 converts the analog output signal from the light detection device 34 into each digital signal. A combined processor 38 processes the digitized photodetector output signal and generates a respective indication that a shadow condition exists in at least one or more of the photovoltaic modules. The processor 38 can be configured to uniquely associate a given optical signal with each PV module and / or string of the power plant. This mapping can be achieved with any desired level of granularity, eg, to allow identification of each PV module area and / or string area that may be shaded. Can be achieved with a certain level of granularity.

  It should be understood that the optoelectronic circuit 22 may be a stand-alone unit and may be integral with an electronic converter or any other unit in the power generation system. If integrated, the installation and / or transportation costs can be reduced.

  In an embodiment, the control device 40 is responsive to each signal from the optoelectronic circuit 22 and takes into account that there may be a shadow state at one or more of each location in the field. It can be configured to implement a control strategy. In one embodiment, the control strategy of the element array can be configured to adaptively control circuit interconnectivity for at least some elements of the element array. For example, the connectivity of series and / or parallel circuits for at least some of the PV modules 12 can be dynamically reconfigured based on shadow conditions at one or more of the respective locations of the field. is there. In one embodiment, the inverter control strategy is adaptable based on shadow conditions at one or more of the respective locations of the field. For example, inverter control strategies better handle the altered characteristics of PV module current-voltage (I-V) and power-voltage (P-V) curves that may be in shadow. Can be adapted as such. Thus, the control strategy implemented by the controller 40 cannot resolve the shadow state (eg, it cannot change the direction of the cloud or dissipate the cloud), but any such shadow. It should be understood that it is useful to dynamically adapt the operation of one or more units of the power generation system, taking into account conditions. The controller 40 can be implemented as a stand-alone controller or as part of a PV plant monitoring and control system.

  The following is a conceptual explanation with a simple example. A square field shall be mapped to four quadrants (regions), and four optical fibers shall be arranged to detect solar radiance in each of the four separate quadrants of the field. . For example, if the light intensity of a certain optical signal is relatively low (compared to the light intensity of the remaining three optical fibers), the quadrant corresponding to the signal with a relatively low light intensity may be shaded. High nature. Similarly, for example, if the light intensities of two optical signals are relatively low (compared to the optical intensity of the remaining two quadrants), the two corresponding to the signals with relatively low optical intensities There is a high possibility that the quadrant is shaded. For example, if the light intensities of all four optical signals are relatively low (compared to the expected intensity, eg, the expected intensity during clear weather), the entire field is likely to be shaded.

  As will be appreciated from the above description, aspects of the present invention provide a cost-effective, fast-response, reliable device for detecting solar radiance irregularities (eg, shadows). They can be used in various solar power generation systems that use an array of elements arranged over a relatively large surface area (eg, a practical scale solar field).

  Although only specific features of the invention have been illustrated and described herein, various modifications and changes will occur to those skilled in the art. It is therefore to be understood that all such modifications and changes are intended to be included within the scope of the appended claims as being within the true spirit of the invention.

DESCRIPTION OF SYMBOLS 10 Solar power generation system 11 Field 12 Photovoltaic module 14 Solar cell 15 Device for detecting unevenness of solar radiance (for example, shadow) 16 Optical fiber 18 First end of fiber 20 Second end of fiber 22 Photoelectric circuit 24 Magnifying lens 30 Data acquisition unit 32 Coupling box 34 Photodetection device 36 Analog-digital converter 38 Processing device 40 Control device

Claims (11)

An array (12) of elements arranged at respective locations in the field (11) and responsive to solar radiance;
A plurality of optical fibers (16) having respective first ends (18) coupled to the element array and configured to receive solar radiance, wherein each of the fields (11); The plurality of optical fibers (16) having respective second ends (20) configured to output respective optical signals representative of respective solar radiances for the location;
Receiving the respective optical signals from the plurality of optical fibers (16) and generating respective signals indicative of the presence of a shadow state in at least one of the respective locations of the field (11); So coupled photoelectric circuit (22);
A control device (40) responsive to said respective signals from said photoelectric circuit (22), wherein said shadow state exists in said at least one of said respective locations of said field (11); In view of the control device (40) configured to implement a control strategy of the element array;
A solar power generation system (10) comprising:   The solar power generation system of claim 1, wherein the element array comprises an array of a plurality of photovoltaic modules.   The solar power generation system according to claim 1, wherein the element array includes an array of a plurality of solar collectors.   The solar power generation system of claim 1, wherein the control strategy of the element array is configured to adaptively control circuit interconnectivity for at least some elements of the element array.   The first end (18) of each of at least some optical fibers (16) of the plurality of optical fibers (16) is disposed near the periphery of the field (11). Item 10. A solar power generation system according to item 1.   The photoelectric circuit (22) comprises a data acquisition unit (30), the data acquisition unit (30) coupled to the respective second end (20) of the plurality of optical fibers (16). The solar power generation system according to claim 1, comprising a main light connection box (32).   The solar power generation system of claim 6, wherein the data acquisition unit (30) further includes a light detection device (34) responsive to the respective optical signals from the plurality of optical fibers (16).   The optoelectronic circuit (22) further comprises a processing unit (38) coupled to the photodetection device (34), wherein the processing unit (38) processes the respective photodetection device output signal and the field ( The solar power generation system of claim 7, wherein the respective signal is generated to indicate that the shadow state exists at the at least one or more of the respective locations of 11).   The solar power generation system of claim 1, further comprising a plurality of magnification lenses (24) optically coupled to the respective first ends (18) of the plurality of optical fibers (16). An array (12) of photovoltaic modules arranged at respective locations in the field (11);
A plurality of optical fibers (16) having respective first ends (18) coupled to the photovoltaic module array and configured to receive solar radiance; The plurality of optical fibers (16) having respective second ends (20) for outputting respective optical signals representing respective solar radiances for the respective locations;
A photodetector (34) responsive to the respective optical signals from the plurality of optical fibers (16);
Coupled with the photo detector (34) to process the respective photo detector output signals, each representing a shadow state in at least one or more of the respective locations of the field (11) A processing device (38) for generating a signal of
A control unit (40) responsive to the respective signals from the processing unit (38), wherein the shadow state exists in the at least one of the respective locations of the field (11); In view of the control device (40) configured to implement a control strategy of the photovoltaic module array;
A solar power generation system (10) comprising:   12. The control strategy of claim 10, wherein the control strategy of the photovoltaic module array is configured to adaptively control circuit interconnect for at least some photovoltaic modules of the photovoltaic module array. Solar power generation system.

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